Q1Written answer
What were the characteristics of life forms that had been fossilized?
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Ans: Life forms had some hard parts such as Bones, teeth, etc. which could be fossilized.
NCERT Exemplar · Class 12 · Biology
Chapter 7: Evolution
Practice each question, then open the answer or worked solution.
Very Short Answer Questions
15 questionsQ2Written answer
Did aquatic life forms get fossilized? If, yes where do we come across such fossils?
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Ans: Yes, aquatic life forms get fossilized. Many of these fossils have been discovered in oil wells. Many more have been discovered in sedimentary rocks as a result of sedimentation filling up many water bodies.
Q3Written answer
What are we referring to? When we say 'simple organisms' or 'complex organisms'.
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Ans: When we say ‘simple organisms’ or ‘complex organisms’ we refer to the complexity of the division of labor, metabolism, and the level of organization in the organisms.
Q4Written answer
How do we compute the age of a living tree?
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Ans: We can compute the age of a tree by counting the number of annual rings or with the help of carbon dating.
Q5Written answer
Give an example for convergent evolution and identify the features towards which they are converging.
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Ans: Flippers of dolphins and penguins are examples of convergent evolution. In both of the organisms, flippers have different origins but perform similar functions.
Q6Written answer
How do we compute the age of a fossil?
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Ans: Age of fossil is computed by using carbon dating. The presence of radioactive carbon is calculated to compute the age of a rock.
Q7Written answer
What is the most important precondition for adaptive radiation?
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Ans: The most important precondition for radiation is common ancestry.
Q8Written answer
How do we compute the age of a rock?
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Ans: The age of the rock is computed by using radiocarbon dating. The presence of radioactive carbon is calculated to compute the age of a rock.
Q9Written answer
When we talk of functional macromolecules (e.g. proteins as enzymes, hormones, receptors, antibodies, etc), what are they evolving?
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Ans: Functional macromolecules are evolving towards living forms.
Q10Written answer
In a certain population, the frequency of three genotypes is as follows:
Genotypes | BB | Bb | Bb |
Frequency | 22% | 62% | 16% |
What is the likely frequency of B and b alleles?
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Ans: Frequency of B alleles = BB +\[\frac{1}{2}\] Bb
= 22%+31%
=53%
Frequency of b alleles =bb+\[\frac{1}{2}\] Bb
=16%+31%
=47%